Various formats may be utilized for optical signal modulation in silicon photonics, including, return-to-zero (RZ) and non-return-to-zero (NRZ) on-off keying (OOK), RZ and NRZ differential phase shift keying (DPSK), quadrature phase shift keying (QPSK), and so forth. Advanced modulation formats such as four-level quadrature amplitude modulation (QAM-4), sixteen-level quadrature amplitude modulation (QAM-16), and four-level pulse amplitude modulation (PAM-4) formats, may also be utilized in complementary metal-oxide-semiconductor (CMOS) based integrated circuits for optical signal modulation. A goal of these advanced modulation formats is to increase the spectral efficiency, i.e., the information rate that can be transmitted over a given bandwidth, of a communication system.